Airscoop for internal-combustion engines



Oct 30,1945. w FLCIMOQK y Y 21,388,213

\ k, AIRSCOOPS FOR INTERNAL-COMBUSTION ENGINES I Filed Nov. 25, 1942 3 shess-sneet 1 FULLCOLD FUR I WARM: PRoTEc-rEo HIR- FRANK C. MOCK a mro xw Filed Nov. 25, 1942 3 Sheets-Sheet 2 zoo E 5 a 6 .z ,3

INVENTOR. FRANK C. MQCK 6?.

ATTORNEY Demo, 1945. RQMQCK 2,388,213

AIRSCOOPS FOR INTERNAL-COMBUSTION ENGINES PARTIAL Ho'r FUR FULL- Ho-r AIR 1 3' 71 v gigs FRANK'C-MOCK ATTORNEY.

Patented Oct. 30, 1945 UNITED STATES 2,388,213 AIRSCOOP FOR INT PATENT" OFFICE ramp-COMBUSTION ENGINES Frank 0. Mock, South Bend, Ind., assignor to Bendix Aviation Corporation, South Bend, ImL, a corporation of Delaware- Application November 23, 194i, Serial No. 466,619 44 Claims. (01. lea-122) for supplying air to the charge formingdevice of an aircraft engine.

As is generally known, most charge forming de vices utilize a venturi or other air metering. element in the air supply passage for-creating a lo suction or a differential pressure which varies in accordance with the air flow to the engine and which is used either directly or. indirectl-y'to determine the rate at which. fuelis supplied to the 18 he. f

Air scoops of the type known in the art have I had inherent characteristics which variably disturb the relationship between the air-flow and o the suctioncreated. by the venturi and consequently interfere with the. proper fuel to air proportioning.- One such, disadvantageous characteristic ofknown types of scoops has been their i inability to maintain a uniform air velocity across the scoop, particularly at the entrance to the charge forming device. This non-uniformjvelocity of the various portions of the moving air column results in a suction at the venturi which is ofv asomewhat different amountfrom the suction which would prevail if the average velocity obtained at all points across the .venturi. As a consequence, the fuel to air proportioning of the charge forming device is disturbed.

One of the reasons for this condition of nonuniform velocities has been due to the design of the scoop proper, as a resultof which the air as column, which generally is diverted by the scoop through an angle of about 90, has a tendency to follow along the back or outer wall of the turn, and cannot redistribute itself across the .scoop in the limited available distance between the turn 40 in the scoop and the entrance of the carburetor or charge forming device. v

The problem of proper-air scoop design to obtain accurate fuel metering has been complicated further by the necessity for heat valves or other arrangements for admittingprotected or heated air to the air scoop at times when an aircraft is encountering atmospheric conditions which tend impeller as aresult of; large'piece's of dislodged The majority of scoops of the'prior art make no provision whatever for supplying heated air to the scoop duringsuch times as it is needed to prevent icing or to aid in warming up the engine; and the few scoops which have made such a provision have an inherent disadvantage, particularly in partialheatoposition, that during operation with the heat on, thecolumn of air entering the charge forming device is not of a uniform temperature but varies between wide limits: he ,-a consequence, icemay be effectively eliminated. in some portions of the carburetor,

but not in others; In order must eflectively to prevent, icing atallpoints inthe scoop and carburetor it i of course desirable that the heated air be'unifo y distributed across the entire carbureto'r P ssage. Furthermore, the'variations in density resulting .from this: temperature variation disturb the suction to airflow relationship.

and adversely affect the accuracy of fuel metering. In addition, the non-uniform temperature makes it diflicult if not impossible so to locate the temperature compensating element of the,

charge forming device that it issubiected at all times to the average air temperatureregardless of. variations both in the rate of air flow, ac-

companying changes'in engine load and speed,

and inthe relative amounts of heated and cold {air supplied, as determined by the degree of opening or the heat valve.

.The scoops known to the prior art have generally been provided with some sort of gate or flap valve generally pivotedto and forming a.

portion of the forward wall of the scoop, and arranged to open, inwardly into the scoop to any angular position to restrict the normal cold air passag and simultaneously open a port to ad'- mit from'under the engine cowling air which has been heated by passing over the engine.

with such an'arrangement, however, the air entering the normal 'cold air opening of the air scoop is diverted by the gate or flap valve so that 7 it followsa path near the back wall of the scoop anki has a relatively great velocity and pressure both because of being, confined to the outer portion ofthe bend and because of the ramming action from the forward velocity of.the plane.

. On the other hand, the heated, air is directed by to formv ice in the'air scoop and/or withinthe induction passage leading to the engine with the 5 I attendant danger'of so clogging with ice the scoop; or induction passagethat continued flight is im-, 1 possible, or possibly damaging the supercharger the valve so that it tendsto'follow the forward wall of the scoop and has a relatively low ve- "locity and pressure because of the resistance to air. flow under the cowling' and because of the absence oframmlng action. I

locity, high pressure air. tends to be cohcentrated Thus cold, high vealong theou'ter or rear wall of the scoop and hot,

low velocity, low pressure air tends to be concentrated along the inner or forward wall of the scoop. This non-uniformity of the air column entering the charge forming device has made it difficult to maintain proper fuel metering.

In addition, since the cold air is at a greater pressure. due to ramming action, than the warm air. it is impossible to obtain a gradual application of heat by gradually opening the flap valve just referred to. Initial opening of the flap valve merely allows a portion of the high pressure cold air to escape through the warm air port, and does not result in the admission of any heated air. With such heat control the valve must be opened a substantial amount before thecold air supply is so restricted that warm air may enter through the warm air port, and thellmited remaining travel of the valve changes the air supply from full'cold to full hot. The heat valve is thus in effective through the initial portion of its range of movement and too sensitive through the remaining portion.

With these and otherproblems in mind it is an object of this invention to provide an air scoop which will insure uniform velocity to the air stream moving through it.

Another object is to provide an air scoop which will provide a uniform velocity air column to the charge forming device.

Another object comprehends' the inclusion of means located in the passages of an air scoop which will insure uniform velocity in the moving air column when it reaches the charge forming device.

Still another object is the provision of a restriction in the air scoop which will divide the moving column of air so that it will have the desirable velocity qualities when it reaches the charge formin device.

Yet another object is to provide a device for supplying air to a charge forming device which is readily adjustable to supplyheated air to the charge forming device at a uniform velocity and pressure, as for example when an aircraft is encountering icing conditions.

Still another object is the provision of means at the control of the pilot or flight engineer whereby there will be given "feel to the operator, so that the position of the control for admitting cold, protected, or heated air to the scoop and to the charge forming device will be known to the operator.

Another object comprehends a dual means of supplying a column of air to the charge forming device which has been heated either by 1) passing over the engine and protected by the cowling and known as warm protected air, or (2) passing between the exhaust manifold and a jacket surrounding the manifold and known as hot air.

Another object of the invention is the provision of a heat control arrangement in which the cold air inlet is fully closed during operation in the warm protected air position. This is of particular advantage in that rain or snow may be entirely excluded without the resultant loss of power accompanying the use of full heat.

-Yet another object comprehends the supplying of air to the charge forming device which may be heated to some temperature between 1) and (2) above and may be supplied to the charge forming device at the control of the pilot or the flight engineer.

A still further object is the provision of me s foreliminating icing by fully shutting ofl the entrance of a cold stream of air and concurrently opening an entrance to provide heated air to a charge forming device.

Still another object of the invention is the provision of a means whereby heated air may be supplied even though an obstruction such as ice is on the edge of the cold air door and/or its seating surface.

A still further object is for supplying heated air to a charge forming device, the temperature of the air being selectable as desired depending upon the conditions of flight.

Other features and desirable objects of this invention will be apparent from a study of the description and drawings forming this specification, in which:

Figures 1 and 2 are cross sectional views of a known type of air scoop connected to a, charge forming device and showing various normally experienced velocity characteristics of the moving column of air as it enters the charge forming device;

Figure 3 is a view partially in section of a preferred embodiment of the air scoop made according to the present invention;

Figure 4 is a cross section taken substantially along the line 44 of Figure 3;

Figure 5 is a somewhat schematic cross section of an air scoop made according to the present invention in the full cold air position, the'velocity characteristics of the column of air entering the charge forming device being shown vectorially;

Figure 6 shows in cross section an air scoop made according to the present invention and shown positioned with reference to an aircraft engine, with the heat valve for controlling the entrance of heated air shown in a position whereby warm protected air is admitted to the scoop;

Figure 7 is a cross section of the scoop. shown in the partial hot air position, the scoop being positioned with reference to an aircraft engine and cowling; and

Figure 8 is a cross section of the full hot air position, its erence to an aircraft engine matically.

With reference to Figure 1 there is shown a scoop 20 of a type known to the prior art secured to an entrance conduit 22 of a charge forming device which may be of any desired type, the one shown at 24 being of the type disclosed in my cothe scoop shown in location with refbeing shown schepending application Serial No. 362,572, filed Octo-' ber 24, 1940. The charge forming device 24 may comprise a boost or primary venturi 26 and a main or secondary venturi 28 for determining the metering of fuel to a column of air which is supplied to an aircraft engine.

The path of the moving column of air is indicated generally by the light lines 30, the spacing of the lines being proportional to the velocity of the moving air column, 1. e. lines which are close- 1y spaced indicate points of higher velocity, and

lines which are relatively widely spaced indicate points of lower velocity. The velocity vectors indicated at 32, and the vector diagram of the air stream entering the primary venturi 28 is shaped. for example, in the form of a composite rectangle and trapezoid. The vector diagram, sometimes referred to as the velocity pattern, is not at all stable for known types of scoops but will change with variations in the rate of air flow, the angle of attack of the plane or with other variations in flight conditions. i

the provision of means With reference to Figure 2 there is shown a 2I0 located adjacent the secondary venturi 266, the pressure in the venturi 206 and the pressure transmitted through the tubes 2I0 being utilized to determine the proper metering of fuel.

tors may be represented in the vector diagram I32, which is trapezoidal in shape, showing the lowest value of the velocity vector adjacent the forward wall of the scoop I20, and varying substantially uniformly to the highest value at the back wall of the scoop.

However, the velocity characteristics of the moving column of air in scoops known to the prior art may take different forms. Sometimes the characteristic has a recognizable regular pattern while at other times the velocity distribution is quite irregular and not in accordance with any known pattern.- In general, however, relatively high velocities tend to prevail adjacent the back wall of the scoop and relatively low velocities adiacent the front wall.

The scoops which have been shown in Figures 1 and 2 may be of a type which is rectangular in shape at the forward opening adjacent the cowling of the aircraft engine, and which may vary in contour so as to fit top decks 23 and I23 of the charge forming devices 24 and I24 'at a point anterior to the primary venturis 26 and I26, Although the scoops 20 and I20 generallyhave rectangular entrances they may have elliptical shaped entrances, for example, or circular, depending largely upon designers choice. However, a preferred type has an entrance which is rectangular, preferably with the minimum dimension in the vertical plane, the body thereofbeing also rectangular and faired to meet the dimensions of the top deck of the charge forming device.

A preferred embodiment of the scoop made according to the present invention i shown in Figures 3 and 4. This embodiment has been found to be particularly satisfactory for the purposes intended, but it is to be understood that the invention is not to be limited to the embodiment shown, other arrangements falling within the spirit and scope of this invention to be permitted according to the claims appended to the end of this description.

The air scoop which is indicated generally by the ordinal 200 i adapted to be flexibly mounted on an adapter 20I which in turn is secured in any known manner to the top deck 202 of a charge forming device indicated generally by the ordi- The scoop 200 comprises an entrance passage 2I2 which receives a moving column of air, the velocity of which is given to it by the propeller wash, the movement of the aircraft through the air and the suction created by operation of an internal combustion engine. The entrance pas-.

sage 2 I2 extends in a generally horizontalidirection until it intersects a riser 2I4 of the scoop 200 forming a throat 2 I6. The throat 2 I6 has a cross section as indicated and is formed by a curved outwardly bulged back wall 2I6 faired into an upper wall 220 of the entrance passage 2I2, and

into a back wall 2220f the riser 2| .4, and by a forward curved wall 224 which connects a lower wall 226 of the entrance passage 2I2 and a for-- ward wall 228 of the riser 2. A rotary door or heat valve 226 forms a part of the forward curved wall 224 when the scoop 200 is in the full cold air position as shown in Figures 3 and 4. The door 228 is rotatable to positions other than that shown in Figures 3 and 4 to permit the entrance of protected or heated air to the scoop 200 and the charge forming device 204. The detailed description of the rotary door 226 and it operation will appear later in this specification.

Within the throat 2 I6 is positioned an isla generally of the shape indicated in Figur 3. While the shape shown has en found to be preferred for the purpose desired, it is shown for purposes of illustration only, other shapes and contours fulfilling the purpose being within the scope of this invention.

The island 230 is secured to the scoop 200 in any known manner as by cap bolts 232 passing through suitable holes in flanges 234 attached to the island 200 and threaded into the scoop 200. The island 230 has a relatively sharp leading edge 236 which preferably occupies a-position vertically disposed from the horizontal plane which bisects the entrance 2I2 of the scoop 200 and preferably above said plane in the manner shown. Starting at the leading edge 236 the contour of the island 260 is such that its upper surface 238 and trailing surfaoe 230 are spaced from the walls nal 204. The flexible mounting for the scoop 200 may be an elastic boot 200 which is fastened to the scoop 200 and the adapter 20I, as by clamping rings 206. This assembly will permit. move-, ment between the scoop 200 and the charge forming device 204, and is ordinarily necessary, since the scoop may be secured to a structure, as for example, an aircraft, and since'the engine on which the charge forming device 204 is generally supported may be somewhat flexibly mounted with respect to the aircraft or supporting structure.

The charge forming device 204 may include a boost or primary venturi 206, a main or secondary venturi 206, and a plurality of impact tubes 220 and H8 and generally varying in distance from the walls 220 and 2I8 according to the desired function of the scoop 200. Again starting at the leading edge 236 the contour of the island 2301s such that a forward surface 242 varies in distance from the curved forward wall 224 according to a-desired function latertdescribed in this specification. The island 220 may, terminate. as shown. in a substantially transversely extending surface 244, which, if desired, may be somewhat rounded, to complete the outline of the island.-

Between the upper wall 220 and the curved'wall 2I6 is positioned a thickened portion 240 which is faired into upper wall 220 and curved wall 2l8 so that smooth flowing surfaces are presented to for the moving air column. Since this restriction I in area between surface 230 and the surface at 240 to the moving air column gives way to increasing areas between .the curved wall H8 and the trailing surface 226, and since the surfaces presented are smooth and unbroken, the velocity of the air flowing around the outside ofthe island is gradually decreased.

Between the forward surface 242 of the island 288-and the forward curved wall 224 of the scoop 288 are distances which vary substantially uniformly from a maximum at the leading edge 288 p of the island 288 to a minimum at the intersection of forward surface 242 with surface 244 and near the point where curved wall 224 fairs into the forward wall 228 of'the riser 2. The disposition of the island 288 with the curved wall 224 serves to constrict the area of the moving .air column which has been divided at the sharp edge 288 of the scoop 288, thereby changing the velocity thereof. Assuming that no compression of the moving column of air takes place; the change invelocity of the air column will be in- 4 assasrs shaft 248 to a position where it is spaced from the cupped portion 288. A bolt 288 passes through an opening in the car 284 which is coaxial with the drilled passage-282 and through the drilled passage 282. A spring 288 is fitted over the shank of the bolt 288 and bears against a washer 288 at one end and against the cupped portion 288 of the arm- 218 at'the other end. Spring 288 is loaded" by drawing up a castellated nut 282 threaded on the shank of bolt 288, which also bears against a washer 284. The nut 282 is locked in place by a cotter notshown.

The rotary gate 228 which has been described briefly'withreference to the disposition of the island 288 in the throat 2l8 of the scoop 288 and f the relation of the island '288 with reference to the walls of the scoop, comprises. a portion of a cylinder, which portion is secured to radially exat the intersection thereof with surface 244. f While it is not exactly accurate to assume that no compression of the moving column of air takes place when its cross section is diminished, yet for purpose ofdesign it can be safely assumed.

For at times when it is. desirable to prevent the entrance of air to the scoop 288 which may be ice-laden or otherwise unsuitable for idealengine operation there is provided means at the control of the pilot orflight engineer for. closing off the supply of such air to the engine and to open the charge forming device 284 to a supply of air which has been heated and protected by passing over the engine or, if warmer air is desired, through a jacket placed around the exhaust manifold.

Referring particularly to Figure 4 there is provided a butterfly valve 248 for preventing the entrance of cold air to the charge forming device 288 at such times when it is not wanted.

Butterfly valve 248 is secured to a shaft 248 by any suitable method, preferably by cap screws 288 as shown. The butterfly 248 and its shaft 248 are so located that when the butterfly is in the full cold air position as shown in Figures 8 and 4 it is substantially in alignment with the leading d e 288 of the island 288, that is, a plane through the leading edge 288 will include the butterfly 248. The shaft 248 is lournaled'at each end in roller thrust bearings 252 and 258', which in turn are held respectively in cylindrical extensions 284 and 285 of the scoop 288. The shaft and bearing assembly is securedat its left end by a suitable bearing seal 258 and a castellated nut 288 which is locked in position by a cotter, not-shown. The entire assembly just described is protected against the elements by a cap 288 which is pressed over 221151: exterior surface of the cylindrical extension The right end of the shaft 248, which is journalled in bearing 258, has aflixed thereto and abutting a shoulder in the shaft 248 a member 282 which includes a sealing ring 288 for hearing, 288 and which is secured *to' the shaft 248 by a key 284. Member 282.has a cylindrical extension 288 around which is freely mounted a. collar 268 integral with an arm 218 of a cam follower. 212.

The entire assembly is. secured by a washer 214 and a castellated nut 218 threaded to the shaft 248 and held against turning by a cotter 218.

The arm 218 has a cupped portion 288 with a drilled passage 282 the axis of which is normal to the axis of the shaft 248 and spaced therefrom. An ear 284 projects from member 282 and extends in a direction parallel to the axis of the tending arms 288 in the manner shown; Radial arms 288 have split ends' 288 which are clamped rigidly to a shaft 888 by bolts 882. shaft 888 is Journaled at its left end in a suitable bearing 884 which in turnis held in an annularportion 888 y of a circular plate 88.1 which is held to the scoop 288 by bolts 888 spaced equally nearthe periphcry of the plate 881. The shaft 888 and bearing 884 is held at-the left end by a flanged seal 888 .for bearing 884 and a castellated nut 8l8 threaded on shaft 888 and secured thereto by a cotter not shown. The entire assembly is closed by a cap 8l2 which fits over the outer surface of the annular portion 888.

The right end of the shaft 888 is ,iournalled in a bearing 8 held in a cylindrical extension 8l8 on the scoop 288. The bearing 814 is sealed by a ring 8| 8'exterior to the bearing. Posed on i the portionof the shaft 888 which extends beyond its Journal in bearing 8 and the bearing seal 8" is a cam 828 which is essentially circular in shape and whichwhas a guide 822 for the cam follower 212. Mounted exterior to the cam 828 is a pulley 824 which can be driven by a cable 828 fromv a control 828 in the cockpit over .a suitable system of pulleys or the like which are not shown.

The cam 828 and the pulley 824 is secured to shaft 888 bya key 888. Cam 828 and pulley 824 are secured against axial movement on the shaft 888 by means of a. washer 882 and a ca'stellated nut 884 secured in turn by a cotter not shown.

The entire right-hand assembly described above is protected against the elements by a fairing 888 secured to the scoop 288 by any suitable means, which are not shown.

' Cam 828has ahub 82l which is integral with a web .828 and the'guide 822. Secured to web 828 is 9. lug 825, shown in dotted outline in Figure 3,

. which engages a step 821 which is integral with the cylindrical extension8l8. When the lug 828 and stop 82'! are in contact the scoop is in the full cold air position as, shown in Figure 3. For limiting the rotation .of the cam 828 and its attendant rotary door 225 in the clockwise direction a nose 828 of the cam 828 engages the other face of the stop 821.

Cam 828 has a contour as shown, and its guide 822 is composed of two circular portions 888 and 885, portion 888-being of a smaller mean radius than portion385 and being smoothly joined thereto at one end by a reverse curved portion 888. Portion 888 is Joined to a portion 881 which is parallel to a radius of the cam 828.

Scoop 288 has a pair'of passages 848 and 842 which are in respectivecommunication to warm protected air and to hot air. Passage 848 has an aaeaaia webs being also the same as or slightly'less than the chord length of the door 225.

The operation of the scoop which has been described with reference to Figures 3 and 4 is as follows.

The arrangement of parts shown in Figures 3 and 4 are those for normal flight conditions,

that is, the air supplied to the charge forming device 264 does not need to be warmed to prevent icing, nor is the entering air column laden with ice. During such time the entering air column is passed at impact pressure through the scoop 266 in the manner shown in Figure 5, which shows in detail the change in the velocity characteristics of the air column as it passes around the island 236.

With particular reference to Figures 3 and 5, the entering column of air, which is divided by the island 236, is subjected to changes in velocity which has been described partly with reference to.

Figure 3 above. The air which passes above the butterfly 246 is first accelerated by the Venturi action between surfaces 246 and 238v and 239 and then decelerated' thereafter since the cross sectional area between curved surface 2i6 and the trailing surface 236 becomes increasingly larger. This change in the velocity of the moving air column which courses in the upper half of the scoop 266 helps to equalize'or average the velocity of the moving air column when it reaches 3 the top deck 262 of the charge forming device Similarly,

to Figures 3 and 5,

and again with particular reference the air which enters the scoop 266 and is divided by the butterfly 246 is 40 changed in velocity by the island 236. The position of the forward surface 242 of the island 236 with reference to the curved wall 224 and the gate 225 is such that' a moving column of air. between the surfaces of the elements just 4 mentioned is gradually constricted in cross sectional area, thereby accelerating it.

This function of the sc'oop 266, to decelerate one part of the moving air column and accelerate the other part results in the velocity characteristics of the moving column of air where it enters the charge forming device 264 to be uniform in character. The representation of the uniform character of the moving air column as it enters the charge forming device is shown by 55 the velocity vector diagram 356 of Figure 5, the vectors being shown of the same length to represent equal values.

For at times when the aircraft is encountering, icing conditions the I 266 is closed and air which has been warmed by passing over the engine or between an exhaust manifold jacket and the exhaust manifold is sup- The formingdevice 264. v

plied to the charge under such conditions operation of the scoop as follows.

The pilot or the flight engineer will move the control handle 328 in a clockwise direction thereby imparting a similar movement to the pulley 324 through the cables 326. By the clockwise 7n rotation of the pulley 324 a similar rotation is imparted to the shaft 366 and cam 326. This first movement serves to shut the butterfly 246 and move the rotary door 225 to the-warm or protected air position,

butterfly 246 of the scoop a webs 346 and 346 will be closed and the passage between webs 346 and 344 will be open.

The air and any entrained rain or snow entering through the main impact opening 2 I2 is thus cut off and the carburetor is supplied with protected or non-impact air taken from under the engine cowling 352. as best shown in Figure 6. The protected air, so called since it is substantially free of any entrained rain or snow which is deflected or deposited out of the air supplied to the carburetor by virtue of the tortuous path through which the air flows, is warmed by passing between the engine and its cowling.

Simultaneous with the movement of the rotary door 225 to the warm protected air osition is the closing of the butterfly valve 246. ,This is effected by the movement of arm 216 and its follower 212 in the guide 322 of the cam 326. This movement is transmitted to the member 262 through spring 268 and the ear 284 of member 262. The angular movement of cam 326 induces closing completely, it is still possible to move the rotary door 225 to the position whereby warmed air canbe'admittedli The overrunning connectionprovided by the spring 288 mounted on the bolt 266 permits a certain amount of angular travel 'of the arm 216 relative to the butterfly 246 to closed position, there still is the free angular travel of the arm 216 caused by the movement of the cam 326, thereby insuring against damage to the'parts shouldvice be present in the entrance passage 2l2.

However, the angular travel of thebutterfly 246 to the closed position is less than the angular travel required by the rotary door 225 to move from the cold air position of Figure 3 to the warm 3 Consequently, should the presence yof ice prevent 'thefull angular travel of the butterfly protected air position where the rotary door 225 will clo e the passage between webs 346 'and 348.

I To per it this added angulartravel, and not to i change the position of the, butterfly 246, which now would e in the closecl positiomthe portion 333 of the earn 326 base uniform radius. When the cam 326 has moved through such an angular distance the cam follower 212 will ride on the reverse curved portion 338. At such time the door 225 is in the warm protected air position, and the pilot or flight engineer is given "feel through the cables 326 for telling him the rotary door 225 has reached such a position. For adjusting the scoop to positions betwee the warm protected air position of Figure 6 and the full hot air position of Figure 8 the cam 326 may be rotated through a further angle as shown in Figure 7., Since the butterfly 246 is already in its closed position, further rotation of the cam 326 and the consequent engagement of the.follower 212 with the'cam portion 335 slightly rotates the lever 216 in a counterclockwise direction compressing the spring 268 and apprlsing the pilot that the door "225 has moved beyond its warm protected air position toward its hot air position. i

When the cam 326 has moved to the limitof its clockwise angular travel, which travel is stopped by the engagement of nose 329 of cam 326 with whereby passage between 7; stop 32'! the scoop 266 will be in the full hot air position of Figure 8, and the passage 340 between webs 344 and 346 will be closed by the rotary door 225.

Again with reference to Figures 6, '7 and 8 there is shown diagrammatically the position of the rotary door for the particular desired type of heated air supplied to the aircraft engine and charge forming device. In other than the full cold air position the rotary door 225 preferably should occupy either the warm protected air position or the full hot air position; however, if desired it may occupy the intermediate position shown in Figure 7. Figures 6, 7 and 8 also show the path of the heated air through the scoop 200. The suction created across the top deck of the charge forming device by the engine and supercharger draws the air around the island 230 in the manner shown. Since the butterfly 246 is closed at all positions other than the full cold air position, there is no possibility that the air entering the charge forming device 204 is composed of strata containing warmed air and cold air. As has been explained at the outset of this specification, such a. condition results in inaccurate metering of fuel since the quality of the air supplied to the charge forming device is not uniform.

Thus has been described a novel and useful improvement in devices for supplying air to a charge forming device for an internal combustion engine. The embodiment of the invention described has been found to be a particularly suitable one for the purposes intended, but it is to be understood that the scope of the invention is in nowise limited to the embodiment shown, nor otherwise than by the claims appended hereto.

I claim: i

1. A scoop for supplying a moving column of air to a charge forming device for an internal combustion engine comprising means for at times preventing the entrance of air at atmospheric conditions, means for controlling .the entrance thereto of air from at least one of a plurality of heating sources, and means coupled with said second means for closing said first means to prevent entrance of air at atmospheric condition when said second means admits the air from said plurality of heating sources.

2. A scoop for supplying a moving column of air to a charge forming device comprising a passage open to air at atmospheric conditions, a riser connected to said charge forming device and intersecting said passage, means in said passage for at times preventing the entrance of air at atmospheric conditioma plurality of passages each connected to a source of heated air and having a common opening in the wall of said scoop, a door for .said opening preventing the entrance of heated air to said scoop when said first passage is open to air at atmospheric condition,'and means connecting said door and the first said means for closing the passage to air at atmospheric conditions when said door is opening to permit the entrance of heated air to said scoop.

3. A scoop for supplying a moving columnof air to acharge forming device comprising a passage for admitting air at atmospheric conditions, a riser connected to said charge forming device and intersecting said passage, means in said passage for at times preventing the entrance of air at atmospheric conditions, a plurality of passages each connected to a source of heated air and having a common opening in the wall of said scoop, a rotary door in said passage for preventing the entrance of heated air to said scoopwhen said first passage is open to air at atmospheric condition, and means comprising a cam connected to said door-and a cam follower and arm connected to said first means for simultaneously closing the passage of air at atmospheric conditions when said door is opening to permit the entrance of heated air to said scoop.

4. A scoop for supplying a moving column of air to a charge forming device comprising a passage for admitting air at atmospheric conditions, a riser connected tosaid charge forming device and intersecting said passage, a normally open butterfly valve in said passage, a plurality of passages each connected to a source of heated 'airand having a common opening in the wall of said scoop, a rotary door in said passages, and means I connecting said door and said butterfly for simultaneously closing the butterfly valve upon opening of the said door.

5. A scoop for supplying a moving column of air to a charge forming device comprising a passage for admitting air at atmospheric condition, a riser connected to said charge forming device and intersecting said passage, a butterfly in said passage for normally permitting the entrance of air at atmospheric conditions, a plurality of passages each connected to a source of heated air and having a common opening in the wall of said scoop, a door for said opening, and means comprising a cam connected to said door and a cam follower and arm connected to the butterfly for closing the butterfly when said door is moved toward open position.

6. A scoop for supplying a moving column of air to a charge forming device comprising a passage for supplying air at atmospheric condition, a riser connected to said charge forming device and intersecting said passage, means in said passage for normally permitting the supply of air at atmospheric condition, a passage connected to a source of heated air and having an opening in the wall of said scoop, a rotary door for said opening, and means comprising a cam connected to said rotary door and a cam follower and arm connected to said first means for closing the passage to air at atmospheric condition when said door is moved to open position.

7. A scoop for supplying a moving column of air to a charge forming device comprising a passage for supplying air at atmospheric condition, a riser connected to said charge forming device and intersecting said passage, a butterfly in said passage for normally permitting the supplyof air at atmospheric condition, a passage connected to a source of heated air and having an opening in the wall of said scoop, a, rotary door for said opening, and means connecting said door and said butterfly for closing the passage to air at atmospheric conditions when said door is moved to open position. 7

8. A scoop for supplying a moving column of air to a charge forming device comprising a passage for supplying air at atmospheric condition, a, riser connected to said charge forming device and intersecting said passage, a butterfly in said passage, a passage connected to a source of heated air and having an opening in the wall of said scoop, a rotary door for said opening, and means comprising a cam connected to said door and a cam follower and arm connected to the butterfly for closing the passage to air at atmospheric condition when said door is moved to open position.

9. A scoop for supplying a moving column'of air to a charge forming device for an internal combustion engine comprising an entrance passage for air atatmospheric condition, means disposed in said passage for at times preventing the entrance of air at atmospheric condition. means controlling an entrance to said scoop for air from a plurality of heating sources, one of said sources supplying air which has been warmed by. passing over the surfaces of said internal combustion engine, the other of said sources supplying air which has been heated by passing over the surface of an exhaust manifold of said internal combustion engine, and means coupled with said second means for closing said first means to prevent entrance of air at atmospheric conditions when said second means opens the entrance for air from said plurality of heating sources.

10. A scoop for supplying a moving column of air to a charge forming device for an internal combustion engine comprising an entrance passage, means disposed in said passage for at times preventing the entrance of air at atmospheric conditions, a door located at an entrance to said scoop of air from a pluralit of heating sources, one of said sources supplying air which has been warmed by passing over the surfaces of said internal combustion engine, the other of said sources supplying air which has-been heated by passing over the surface of an exhaust manifold of said internal combustion engine, andmeans coupled with said door for closing the first said means to prevent entrance of air at atmospheric condition when said door opens the entrance for air from said plurality of sources.

11. A scoop for supplying a moving column of air to a charge forming device for an internal combustion engine comprising an entrance passage for air at atmospheric condition, a butterfly valve disposed in said passage, means controlling an entrance to said scoop of air from a plurality of heating sources, one of said sources supplying air which has been warmed by passing over the surfaces of said internal combustion engine, the other of said sources supplying air which has been heated by passing over the surface of an exhaust manifold of said internal combustion engine, and means coupled with said second means for clostion for effecting movement of said first means to a position whereby air at atmospheric co'ndition is prevented from entering said scoop when said door is moving to a position where air from one of the plurality of heating sources is admitted to said scoop, a portion on said cam for indicating when said door ismoving to a position where air is supplied from more than one heating source, a stop for said cam whereby the door is positioned to admit air from another heating source, said movementsof the cam subsequent to the movement closing the first said means leaving unchanged the position of the first said means. I

14. In a scoop for supplying air toa charge forming device for an internal combustion engine, means for normally permitting the entrance of air at atmospheric conditions to said charge forming device, means for at times permitting the entrance to said scoop of air from at least one of a plurality of heating sources, a cam connected to said second means and operating the said first means through a cam follower and am, said cam comprising a portion for efiecting the movement of the first means to a position where air at atmospheric conditions is prevented from entering said scoop when said second means is moving to any position whereby air from the plurality' of heating sources can be admitted to the scoop, a portion on said cam for indicating when said second means is moving to a position where an is supplied from more than one heating source, a stop for said cam whereby the said second means is positioned to admit air from an other heating source, said movements of the cam subsequent to the movement closing the said flrst means leavingunchanged the position of the first said means.

15. In a .scoop for supplying air to .a charge forming device for an internal combustion engine, a butterfly for normally permitting the en-,

trance of air at atmospheric condition to said charge forming device, means for at times pering said butterfly to prevent entrance of air at atmospheric condition when said second means opens the entrance for air from said plurality of heating sources.

12. A scoop for supplying a moving column of air to a charge forming device for an internal combustion engine comprising an entrance passage for air at atmospheric condition a butterfly disposed in said passage, a door located at an entrance to said scoop of air from a plurality of heating sources, one of said sources supplying air which has been warmed by passing over the surfaces of said internal combustion engine, the other of said sources supplying air which has been heated by passing over the surface of an exhaust manifold of said internal combustion engine, and means coupled with said door for closing said butterfly to prevent eritrance of air at atmos- I heric conditions when said door opens the enrance for air from saidplurality of sources.

13. In a scoop for supplying air to a charge mitting the entrance to said scoop of air from at least one of aplurality of heating sources, a cam connected to said means and operating the butterfly through a cam follower and am, said cam comprising a portion for effecting the movement of the butterfly to a position whereby air at atmospheric condition is prevented from entering the scoop when saidmeans =is moving to any position where air from the plurality of heating sources can be admitted to the scoop, a position on said cam for indicating when said means is moving to a position where air is supplied from more than one heating source, a stop for said cam whereby the means is positioned to admit air from another heating source, said movements of the cam subsequent to the movement closing the butterfly leaving unchanged the position of the butterfly.

16. The invention as defined in claim 14 wherein the arm is provided with a spring loading for indicating when said door is moving from one of said plurality of heating sources to the other.

1'7. In a scoop for supplying air to a charge forming device, for an internal combustion engine,

a butterfly for normally permitting the entrance of air at atmospheric conditions to said charge forming device, a door for at'times permitting the entrance to said scoop of air from at least one of a plurality of" heating sources a cam con-' position of the butterfly.

18. In an aircraft,'an internal combustion engine with a charge forming device therefor, a. cowling for protecting said engine, an exhaust manifold for said engine, a Jacket around said manifold for heating a supply of air, an air scoop having an entrance passage normally operative to supply a moving column of air to the charge forming device at substantially atmospheric temperature, means for at times permitting the entrance of air which has been warmed by passing over said engine and inside said cowling, said means also permitting at times the entrance of air which has been heated by passing over said manifold, and means coupled 'with said second means for closing said first means to prevent entrance of air at atmospheric condition when said second means permits the entrance of air which has been heated by the heating sources.

19. A fuel and air supplying device for an internal combustion engine comprising in combination: a charge forming device for said internal combustion engine, an air scoop connected to said charge forming device for supplyinga moving column 01- air to the charge forming device including means for normally permitting the entrance of air at atmospheric condition, means for at times permitting the entrance thereto of air from one of a plurality of heating sources, and means coupled with said second means for closing said first means to prevent entrance of air at atmospheric conditions when said second means permits the entrance of air from said plurality of heating sources.

20. In combination with an internal combustion engine having a charge forming device therefor and an-exhaust conduit, an air passage normally operative to supply air at atmospheric temperature to the charge forming device, a second air passage connected to the charge forming device in parallel with the first passage and passing in proximity to the heated portions of the engine to absorb heat therefrom, and a third passage connected to the charge forming device in parallel with the first andsecond passages and including a heating device associated with the exhaust conduit, valve means selectively operative to close either or both of said second and third passages, a second valve means in the first passage, and connecting means between the valve means operative to close the second valve means when the first valve means is moved to a position to open either of the second and third passages, and to open the second' valve means when the first valve means is moved to a position to'close both of the second and third passages.-

21. In combination with an internal combus tion engine having a charge forming device therefor and an exhaust conduit, an air passage normally operative to supply air at atmospheric tem--,

perature to the charge forming device, a second air passage connected to the charge forming device in parallel with the first passage and passing in proximity to the heated portions of the engine to absorb heat therefrom, and a third passage connected to the charge forming device in parallel with the first and second passages and including a heating device associated with the exhaust conduit, a rotary door selectively operative to close either or both of said second and third passages, a second valve in the first passage, and connecting means between the valves operative to close the second valve when the first valve is moved to a position to close either of the second and third passages, and to open the second valve when the first valve is moved to a position to close both of the second and third passages.

22. In combination with an internal combustion engine having a charge forming device therefor and an exhaust conduit, an air passage normally operative to supply air at atmospheric temperature to the charge forming device, a second air passage connected to the charge forming device in parallel with the first passage and passing in proximity to the heated portions of the engine to absorb heat therefrom, and a third passage connected to the charge forming device in parallel with the first and second passages and including a heating device associated with the exhaust conduit, a valve selectively operative to .close either or both of said second and third passages, a plate valve on the first passage, and connecting means between the valves including a spring loaded connection with the plate valve operative to close the plate valve when the first valve is moved to a position to open either of the second and third passages, and to open the plate valve when the first valve is moved to a position to close both of the second and third passages.

23. In combination with an internal combustion engine having a charge forming device therefor and an exhaust conduit, an air passage normally operative to supply air at atmospheric temperature to the charge forming device, a second air pasage connected to the charge forming device in parallel with the first passage and passing in proximity to the heated portions of the engine to absorb heat therefrom, and a third passage connected to the charge forming device in parallel with the first and second passagesv and including a heating device associated with the exhaust conduit, a rotary door selectively operative to close either or both .of said second and third passages, a butterfly in the first passage, and connecting means between the door and the butterfly operative to close the butterfly when the door is moved to a position to close either of the second and third passages, and to open the butterfly when the door is moved to a position to close both of the second and third passages.

24. In combination with an internal combustion engine having a charge forming device therefor and an exhaust conduit, an air passage normally operative to supply air at atmospheric tem perature to the charge forming device, a second air passage connected to the charge forming device in parallel with the first passage and passing in proximity to the heated portions of the engine to absorb heat therefrom, and a third passage connected to the charge forming device in parallel with the first and second passages and including a heating device associated with the exhaust conduit, a valve selectively operative to close either or both of said second and third passages, a second valve in the first passage, and means comprising a cam connected to said valve and a cam follower and arm connected to said second valve operative to close the second valve when the first valve is moved to a position to close either of thesecond and third passages, and to open when said first valve is moved to'a position to close both of the second and third passages...

25. In an elbow-shaped air scoop for an aircraft engine, a valve in the inlet of the scoop, an opening in the inner wall of the turn of said scoop posterior to said valve, a second valve controlling the opening in the inner wall, an island within the scoop positioned in the turn thereof and having its leading edge adjacent the said opening, said island approaching the inner wall of the scoop most closely at a point posterior to the opening, a source of heated air connected to the opening, and means for closing the first named valve when the second valve is opened.

26. The invention as defined in claim 25 wherein the area for flow at the said closest point is smaller than the area of the said opening.

2'7. In an elbow-shaped airscoop for an aircraft engine, a valve in the inlet of the scoop, an opening in the inner wall oi. the turn or said scoop posterior to said valve, a second valve controlling the opening in the inner wall, a source of heated air connected to the opening, an island within the scoop positioned within the turn thereof for dividing the air which enters the scoop inlet or the opening in the inner wall, and means for closing the first named valve when the second valve is opened.

28. In an elbow-shaped air scoop for an aircraft engine, a valve in the inlet of the scoop, an opening in the inner wall of the turn of said scoop posterior. to the valve, a second valve controlling the opening in the inner wall, a source of heated air connected to the opening, an island within the scoop positioned within the turn thereof for dividing the air which enters the scoop inlet or the opening within the inner wall, and means for closing the first named valve when the second valve is opened including a cam connected to the second valve and a cam follower connected to the first named valve.

29. The invention defined in claim 28 wherein the cam follower is provided with a spring override whereby the second valve may be opened with the first valve restrained in a partially open position.

30. The invention defined in claim 28 wherein the opening may be connected to air heated by one of a plurality of heating sources.

31. The invention defined in claim 28 wherein the opening may be connected to air heated by one or a plurality of heating sources, the cam follower is provided with a spring override, and the cam is provided with a contour to indicate when the second valve is moving to admit air from another of said heating sources to'the scoop.

32-. In combination with an internal combustion engine having a charge forming device therefor, an air passage normally operative to supply air at atmospheric temperature to the charge forming device, a second passage adapted to supply engine heated air to the charge forming device, a valve controlling the first passage, a second valve controlling the second passage, and means connecting said valves for closing the first valve and opening the second valve, said connecting means including a spring loaded override connection with the first valve whereby the second valve may be opened with the first valve restrained in a partially open position.

33. In an airscoop for a charge forming device of an internal combustion engine, a cold air inlet,

. a warm air inlet, and valve means operative simultaneously to close one of the inlets upon opening of the other inlet.

34. In an airscoop for an aircraft having a cowling, a cold air inlet receiving air exteriorly the warm air inlet and a cam and follower con- F."

nection between said valves for closing the butterfly valve when the cylinder valve is in open position. l 35. In an elbow type airscoop havingsubstantially right angularly related entrance and riser passages, an elbow-shaped island positioned in the turn of the elbow and bridges thereacross, said island having a relatively sharp leading edge in alignment with the entrance and a trailing end in alignment with said riser, the leading edge and trailing end being connected by separated walls which diverge from the leading edge to the turn of the elbow and thereafter converge to the trailing end, said walls being separated a maximum distance diagonally of the turn,

36. The invention defined in claim 35 wherein the trailing end of the island is more closely adjacent the inner wall of the riser than the outer wall.

37. In an elbow-shaped airscoop for an aircraft engine, a main air inlet adapted to open in the forward direction of the aircraft to be subjected to impact, an air inlet port in the wallet the scoop, an island within the scoop positioned within the turn thereof for dividing the air which enters the main scoop inlet or the inlet port, and valve means controlling the main inlet and inlet port and adapted to close the main inlet when the inlet port is open.

38. In an airscoop for a charge forming device of an internal combustion engine, an inlet for impact air, an inlet for protected air, an inlet for heated air, and valve means for closing the impact air inlet upon opening of either of the other inlets.

39. In a airscoop for an aircraft, an air inlet opening in the direction of travel of the aircraft to be directly subjected to impact, an inlet for protected air receiving air through a tortuous path, an inlet for heated air, and means for closing the first of said inlets upon opening of either of the other inlets.

40. In an airscoop for an aircraft engine, an air inlet subjected to direct impact or the air resulting from forward velocity or the aircraft, an inlet for protected air, an inlet for hot air, and valve means controlling said inlets.

41. In an elbow-shaped airscoop, for an aircraft, a main air inlet subject to impact, an opening in the inner wall of the scoop, a valve in the inlet, a valve in the opening, and a cam and follower connection between the two valves.

42. In an eblow-shaped airscoop for an engine having a main air inlet and a second air inlet in the wallet the airscoop, a valve in the main air inlet, a valve in the second air inlet, and a connection between the valves including a cam having two adjacent substantially arcuate portions of different radii and a substantially radial portion adjacent one of the arcuate portions.

43. In an elbow-shaped airscoop having angulariy related inlet and outlet portions, an island immovably fixed in the turn of the scoop dividing the turn into inner and outer passages in parallel comprising a leading edge in alignment with the inlet portion, a trailing edge in alignment with the outlet portion, and inner and outer island surfaces interconnecting said edges and diverging from the leading edge to the turn of the scoop and thereafter converging toward the trailing edge. said surfaces and the walls of the ment with the outlet portion whereby the turn scoop being of. such relative contour that the of the scoop is divided into two passages in parratio of the inlet to outlet erossseotlonal areas allel, the outer wall of the turn 01' the scoop and of the inner passage is greater than the ratio of the outer surface of the island being of such relathe inlet to outlet crosssectlonai areas of the 5 tive contour that the outer passage turns through outer passage.

44. In an elbow-shaped airscoop having anguoutlet portions and is of greater cross-sectional larly related air inlet and air outlet portions,. area adjacent the trailing edge of the island than an island immovably fixed in the turn of the adjacent the leading edge thereof. scoop having a leading edge in alignment with lo the inlet portion and a' trailing edge in align- FRANK C. MOCK. 

